1. Field of the Invention
The present invention relates to hybrid lens systems, and more particularly to hybrid lens system typically incorporated in digital camera modules of mobile phones.
2. Description of Related Art
Conventionally, lens systems used in digital cameras are classified into three types: all-glass lens systems, all-plastic lens systems, and hybrid lens systems. When all-glass and all-plastic lens systems are used in digital camera modules of mobile phones, there are generally some shortcomings. The all-glass lens system is heavy and expensive, so that it is difficult to satisfy the requirements of low weight and low cost. The all-plastic lens system is light and cheap, but can be easily damaged by environmental factors such as high temperatures, scraping, etc.
A conventional hybrid lens system includes the following three lenses arranged in order from an object side to an image side: a front positive biconvex lens, a middle negative biconcave lens, and a rear positive biconvex lens. The front positive biconvex lens and the middle negative biconcave lens are made of inexpensive plastic material. The rear positive biconvex lens is made of glass material. Aberration correction at a high relative aperture is improved by the use of aspheric surfaces at selected faces of the front positive biconvex lens and the middle negative biconcave lens.
When used in small-sized mobile phones, the front positive biconvex lens is liable to be scraped by a user's fingers or other objects. Further, the front positive biconvex lens is liable to be deformed if exposed to high temperatures. Accordingly, the imaging quality of the conventional hybrid lens system may be significantly reduced.
Thus, what is needed is a hybrid lens system which is capable of resisting scraping and providing improved imaging quality. What is also needed is a mobile phone employing such a hybrid lens system.